import sequtils, sets

var # creation
  s = [0, 3, 5, 10].toHashSet
  t = toSeq(3..20).toHashSet + toSeq(50..55).toHashSet

if 5 in s: echo "5 is in!" # element test

var
  c = s + t # union
  d = s * t # intersection
  e = s - t # difference

if s <= t: echo "s ⊆ t" # subset

if s <  t: echo "s ⊂ t" # strong subset

if s == t: echo "s = s" # equality

s.incl(4) # add 4 to set
s.excl(5) # remove 5 from set